Figure 2.

Overall activity counts by hour in C57BL/6J mice during baseline alcohol access and environmental CD. (A) Patterns of wheel-running behavior varied dramatically between the baseline and experimental photoperiods, with lower activity in the 18HR photoperiod compared to baseline from 7:00–13:00, and greater activity from 17:00–23:00. Mice also showed lower activity in the 12HR photoperiod compared to baseline from 8:00–10:00. (B) Patterns of alcohol drinking also varied by photoperiod. From 24:00–7:00, mice displayed greatest activity in the 18HR photoperiod. Mice were also more active in the 12HR photoperiod compared to baseline from 5:00–7:00. Alcohol intake in the 18HR photoperiod was significantly lower than baseline from 11:00–20:00, and in the 12HR photoperiod it was significantly lower than baseline from 12:00–20:00. From 21:00–24:00, drinking during both CD photoperiods was higher than at baseline. (C) There were few changes in water intake between photoperiods. The only significant difference was higher water intake at 18:00 in the 12HR photoperiod compared to baseline (data indicate the mean ± SEM for n = 8).